Silicon precipitation via photoinduced reaction using femtosecond laser

Silicon precipitation inside a glass is an important technique for silicon photonics. We successfully precipitated silicon inside silicate glasses containing an Al metal film using femtosecond laser irradiation. First, the Al-inserted sandwiched glass was fabricated by the direct bonding method. The results of a tensile test indicated that the adhesive strength of the sandwich structure reached approximately 4 MPa. Next, femtosecond laser pulses were focused at the Al/glass interface in the sandwich structure. A transmission electron microscopy photograph at the focus of the laser showed that the Al particles were dispersed into the glass substrate to a depth of approximately 2 microm from the initial Al layer. In addition, Raman spectra indicated that silicon had formed at the interface between the glass and Al film after the laser irradiation. The morphology or the particle size of the precipitated silicon was successfully modified by changing the repetition rate or the pulse energy of the laser.     

Magnetic Properties of Ru-rich Ru2?x Fe x CrZ (Z=Si, Ge)

The properties of Heusler compounds Ru_2?x Fe _x CrGe are investigated and compared with those of Ru_1.9Fe_0.1CrSi. Ru₂CrGe is confirmed to exhibit an antiferromagnetic transition with Ne??l temperature 13?K by magnetic susceptibility and specific heat measurements. When Fe is substituted for Ru, a peak in the magnetic susceptibility is observed, and in the lower temperature region irreversibility between temperature dependences of magnetization for zero-field-cooling and field-cooling conditions is found. Nevertheless, in specific heat of Ru_1.9Fe_0.1CrGe, there is no anomaly to indicate phase transition. The specific heat is almost identical to that for Ru_1.9Fe_0.1CrSi. The above results demonstrate that the magnetic states in the low temperature region of Fe-substituted samples are spin-glass-like states. Slight substitution of Fe for Ru destroys the long-range-order and lead to peculiar spin-glass-like states.     

Half Cycle Terahertz Pulse Generation by Prism-Coupled Cherenkov Phase-Matching Method

Nonlinear optical terahertz wave generation is a promising method for realizing a practical source with wide frequency range and high peak power. Unfortunately, many nonlinear crystals have a strong absorption in the terahertz frequency region. This limits efficient and widely tunable terahertz wave generation. The Cherenkov phase-matching method is one of the most promising techniques for overcoming these problems. We propose a prism-coupled Cherenkov phase-matching method, in which a prism with a suitable refractive index at terahertz frequencies is coupled to a nonlinear crystal. We demonstrate prism-coupled Cherenkov phase-matching terahertz generation using the DAST and LiNbO₃ crystals. With a DAST crystal, we obtain a spectral flat tunability up to 10 THz by difference frequency generation. With a LiNbO₃ crystal, we observe a spectral flat broadband terahertz pulse generation up to 5 THz pumped by a femto second fiber laser. The obtained temporal waveform is an ideal half cycle pulse suitable for reflection terahertz tomography.     

Effect of spectral irradiance distribution on the outdoor performance of amorphous Si//thin-film crystalline Si stacked photovoltaic modules

Effects of spectral irradiance distributions on the outdoor performance of amorphous Si//thin-film crystalline Si stacked photovoltaic (PV) modules installed at Shiga-prefecture in Japan have been investigated. Outdoor solar spectrum measurements revealed that more than 95% of annual total spectra were blue-rich compared to AM1.5 standard solar spectrum. The outdoor performance of the modules had a higher spectral dependence than that of polycrystalline Si modules. Also, the peak of the histogram of annual spectral indexes well corresponded to the peak of the outdoor performance. The results indicate that the actual spectral irradiance distribution is important in designing stacked PV modules.     

Toward stabilized 10% efficiency of large-area (>5000 cm) a-Si/a-SiGe tandem solar cells using high-rate deposition

This paper reviews recent progress in large-area a-Si/a-SiGe tandem solar cells at Sanyo. Optimized hydrogen dilution conditions for high-rate deposition of hydrogenated amorphous silicon (a-Si:H) films and thinner i-layer structures have been systematically investigated for improving both the stabilized efficiency and the process throughput. As a result, a high photosensitivity of 10⁶ for a-Si:H films has been maintained up to the deposition rate of 15 Å/s. Furthermore, the world's highest initial conversion efficiency of 11.2% which corresponds to a stabilized efficiency of about 10% has been achieved for a 8252 cm² a-Si/a-SiGe tandem solar cell by combining the optimized hydrogen dilution and other successful technologies.     

Rule pool updating through Sarsa‐learning to improve adaptability in changing environments

Genetic network programming (GNP) is a new evolutionary algorithm using the directed graph as its chromosome. A GNP‐based rule accumulation (GNP‐RA) method was proposed previously for multiagent control. However, in changing environments where new situations appear frequently, the old rules in the rule pool become incompetent for guiding the agent's actions, and therefore updating them becomes necessary. This paper proposes a more robust rule‐based model which can adapt to the environment changes. In order to realize this, Sarsa‐learning is used as a tool to update the rules to cope with the unexperienced situations in new environments. Furthermore, Sarsa‐learning helps to generate better rules by selecting really important judgments and actions during training. In addition, the ε‐greedy policy of Sarsa enables GNP‐RA to explore the solutions space sufficiently, generating more rules. Simulations on the tile world problem show that the proposed method outperforms the previous ones, namely GP and reinforcement learning. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Diversifying risk in portfolios using a variable‐size genetic relation algorithm

One important concept in financial risk management is the diversification process of capital allocation. This paper proposes an evolutionary approach for the optimal diversification when making asset allocation using variable‐size genetic relation algorithm (vs‐GRA), whose main role is to model and evolve structures toward effective and diversified portfolios through its graph structure. Simulations using heterogeneous and globally located asset classes in the United States, Europe, and Asia show that the proposed scheme offers competitive economic advantages. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Fuzzy intertransaction class association rule mining using Genetic Network Programming for stock market prediction

Intertransaction class association rule (interCAR) has the ability to find the relationships among attributes from different transactions, which has shown its effectiveness for stock market prediction. A crisp interCAR mining method based on Genetic Network Programming (GNP) has been studied in our previous work. But, the crisp method loses much useful information in the discretization and it has many unstable factors influencing the prediction results, so more information is desired in order to make the prediction safer and more efficient. In this paper, a fuzzy interCAR mining method is proposed to keep as much information as possible in the data transformation. Besides, the proposed method has ability that the trading actions bring large profits. The proposed method is applied to Tokyo Stock Exchange, where we compared it with the crisp method as well as some other methods. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

EvoCMAR: A New Evolutionary Method to Directly Mine Association Rules for Classification

In this paper, we propose an evolutionary method with a three‐layer structure to directly mine association rules for classification. The association rules have been demonstrated to be useful for classification, such as classification based on association rule (CBA) and classification method based on multiple association rule (CMAR), and they are found to be more accurate than some traditional methods, such as C4.5. Generally speaking, there are two phases in an associative classification method: (i) association rules mining; (ii) classification by association rules. However, the two phases are almost separated, viz, during the first phase, the mining of association rules does not focus on classification. Moreover, when building the classifier in the second phase, most of the association rues will be pruned. As a result, if we are able to directly mine the classification association rules, we can save time. Meanwhile, we can expect even better accuracy because the mining procedure itself considers the classification. In this paper, we build a novel evolutionary method, named evolutionary classification method based on multiple association rule (EvoCMAR), to tackle these problems, and the simulation results show that it performs well in both accuracy and speed. © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

The Role of Leaky Gut in Nonalcoholic Fatty Liver Disease: A Novel Therapeutic Target

The liver directly accepts blood from the gut and is, therefore, exposed to intestinal bacteria. Recent studies have demonstrated a relationship between gut bacteria and nonalcoholic fatty liver disease (NAFLD). Approximately 10–20% of NAFLD patients develop nonalcoholic steatohepatitis (NASH), and endotoxins produced by Gram-negative bacilli may be involved in NAFLD pathogenesis. NAFLD hyperendotoxicemia has intestinal and hepatic factors. The intestinal factors include impaired intestinal barrier function (leaky gut syndrome) and dysbiosis due to increased abundance of ethanol-producing bacteria, which can change endogenous alcohol concentrations. The hepatic factors include hyperleptinemia, which is associated with an excessive response to endotoxins, leading to intrahepatic inflammation and fibrosis. Clinically, the relationship between gut bacteria and NAFLD has been targeted in some randomized controlled trials of probiotics and other agents, but the results have been inconsistent. A recent randomized, placebo-controlled study explored the utility of lubiprostone, a treatment for constipation, in restoring intestinal barrier function and improving the outcomes of NAFLD patients, marking a new phase in the development of novel therapies targeting the intestinal barrier. This review summarizes recent data from studies in animal models and randomized clinical trials on the role of the gut–liver axis in NAFLD pathogenesis and progression.